Amid all the tragedy and heroism of World War II, there also were some bizarre occurrences, such as German scientists’ efforts to build flying saucers and create tiny bombs concealed in chocolate bars. But perhaps the weirdest, most inexplicable event in the war was a Japanese air raid on Los Angeles in the early morning hours of February 25, 1942. Or at least that’s what people thought it was. Radar operators saw an unidentified intruder on their screens, terrified civilians reported seeing formations of enemy planes, and the personnel manning anti-aircraft batteries lit up the night sky with a horrific barrage of fire—all of them thought they were under attack. When the smoke and the confusion cleared, however, there was no evidence that the enemy had ever been there.

Adding to the mystery, a bizarre photo appeared on an inside page of the Los Angeles Times the next day, showing searchlights converging on what the caption described as an “object” in the sky over Culver City, a suburb of LA. It’s an image that has been studied ever since by UFOologists. For what it’s worth, one such analysis suggests that the object in the photo was 100 feet in width and about 8,000 feet in altitude. Was it an alien spacecraft? A weather balloon? A wayward civilian aircraft? Or was the entire incident, as military officials later suspected, some sort of clever hysteria-inducing psychological warfare trick? Six decades later, we’ve yet to figure it out.

Listen to a 1942 CBS radio report on the incident in the skies over Los Angeles:

As William C. Breuer recounts in his 2003 book, “The Air-Raid Warden Was A Spy, and other tales from home-front America in World War II,” the strange story began a week before on February 17, when President Franklin D. Roosevelt shocked reporters at a White House press conference by acknowledging that Japan was capable of attacking the U.S. mainland. Six days later, Roosevelt was proven right when a Japanese submarine surfaced at night off Goleta, California, eight miles north of Santa Barbara, and fired fifteen shells from a deck gun at an oil facility. The submariners didn’t hit much of anything, but on the other side of the Pacific, propagandists turned the attack into gigantic victory. “Our Submarines Destroy Large U.S. City,” one Tokyo newspaper headline proclaimed.

As an account from the official military history of the Army Air Force during World War II details, the submarine attack put everyone’s nerves on edge on the West Coast. The following day, U.S. Naval Intelligence issued a warning that another attack was expected within 10 hours. Early in the evening, there were reports of flares and blinking lights in the vicinity of Los Angeles’ defense plants, and air defense officials put the city on alert from 7:18 to 10:23 p.m, before calling it off.

Then, early on the morning of February 25, Californians’ worst fears suddenly seemed to materialize, when radar picked up an unidentified object 120 miles away from Los Angeles. Anti-aircraft batteries were put again on ready-to-fire status. The Army Air Force, fearing that its small fighter force might be outnumbered, kept its planes on the ground until it could determine the scale and direction of the attack. Meanwhile, radar operators watched their screens anxiously, as the object flew to within a few miles of the coast. At 2:21 a.m., the regional controller ordered a blackout. It seemed as if Los Angeles would be under assault within moments.

Moments later, the mysterious intruder abruptly vanished from the radar screens. Nevertheless, air defense officials were deluged with callers reporting sightings of enemy planes. Just before 3 a.m., an artillery officer along the coast reported what he described as “about 25 planes at 12,000 feet” over Los Angeles, and a few minutes later, other observers claimed to see a balloon carrying flares over the adjoining coastal city of Santa Monica. Anti-aircraft batteries opened fire. As one witness recalled in a newspaper interview six decades later, “it was like watching a fireworks display.” The official military history describes what then transpired:

From this point on reports were hopelessly at variance. Probably much of the confusion came from the fact that anti-aircraft shell bursts, caught by the searchlights, were themselves mistaken for enemy planes. In any case, the next three hours produced some of the most imaginative reporting of the war: “swarms” of planes (or, sometimes, balloons) of all possible sizes, numbering from one to several hundred, traveling at altitudes which ranged from a few thousand feet to more than 20,000 and flying at speeds which were said to have varied from “very slow” to over 200 miles per hour, were observed to parade across the skies.

The anti-aircraft batteries fired 1,440 rounds of ammunition, and there were reports that four enemy planes had been shot down, including one that supposedly landed in flames in a Hollywood intersection. But no wreckage was found. Just as strangely, the attackers didn’t hit anything with bombs or gunfire either. There were no casualties, except for at least one death from heart failure, and the only damage was caused by shell fragments and automobiles that crashed in the darkness. The anti-aircraft gunners eventually stopped firing, to avoid hitting 40 U.S. P-38 fighters that had arrived to defend the city. But the P-38s, oddly didn’t find any enemy aircraft to fight. They circled and then returned to their home field.

Later that day, Secretary of the Navy Frank Knox told reporters at a press conference that the attack had been a false alarm. That, however, didn’t explain the mysterious object that showed up on radar, or all the witnesses who claimed to have seen the attacking planes. Army officials subsequently developed another hypothesis. The raiders, they speculated, may have been civilian-style light aircraft, launched either from Japanese submarines or from secret airfields established by the enemy in California or Mexico, as a psychological warfare stunt. The mystery never was officially resolved, and in the decades that followed, UFO enthusiasts advanced the notion that the mysterious object may have been an alien spacecraft. Take this with a whole box of Morton’s salt, but one ET-oriented web site offers a suspiciously blurry copy of what is purported to be a memorandum from Army chief of staff George C. Marshall to FDR, in which Marshall supposedly concludes that,

…the mystery airplanes are in fact not earthly, and according to secret intelligence sources they are in all probability of interplanetary origin.

The Fort MacArthur Museum in San Pedro recently staged a reenactment of the 1942 air raid. From YouTube, here’s a vintage CBS radio report on the original incident.

Wilbur Glaze/90 yrs old former member and guard on duty at 27th and Dewy

Springfield,Mo

February 19, 2013, 12:14 pm

I was a member of Headquarters 1st Bn.203 CA(AA) stationed on a bare peice of land,in squad tents.We later took over the Santa Monica Rifle& Pistol range as our headquarters.There were no radars.They hadnt been issued yet.We used hearing Aids.The target was a ballon to check winds aloft.A routine duty assigned to the searchlight Battery.We were armed with ww1 equieptment.
We were on our way to the Phillipines when Pearl Harbor took place our guns had been sent ahead.We had guns meant toshot down WW1 planes and ammo that old. My picture appears on Dougla Air View May 1942 issue.We are all wearing WW1 uniforms I am the one with BAR rifle with flash arrester.We were under orders of 4th interceptor command.Their command post was in Beverly Hills in tents.Jane Withers had just deleivered sandwiches to my post,just before the aleart.Can tell alot more if anyone is interested.